Agricultural grain, such as corn, wheat and the like, is typically stored in large bins of varying types after harvesting. It is known to be desirable for many reasons to sample stored grain and to measure various physical characteristics of the grain periodically at numerous and varied points in situ within bins of all types. Known devices for accomplishing these objectives include spear-like probes that are designed to be forcibly thrust into the grain at preselected points and to predetermined depths. Among the known spear-like probes are those that enable one to extract grain samples and to measure grain temperature, moisture content, or the like, in situ.